The present invention relates generally to photographic exposure equipment, and more particularly, to a photolithography system and method, such as can be used in the manufacture of semiconductor integrated circuit devices.
In conventional photolithography systems, the photographic equipment requires a mask for printing a pattern onto a photo resist coated subject. The subject may include, for example, a semiconductor substrate for manufacture of integrated circuits, metal substrate for etched lead frame manufacture, conductive plate for printed circuit board manufacture, or the like. A patterned mask or photomask may include, for example, a plurality of lines, structures, or images. During a photolithographic exposure, the photo resist coated subject must be aligned to the mask very accurately using some form of mechanical control and sophisticated alignment mechanism.
U.S. patent Ser. No. 09/480,796, filed Jan. 10, 2000 and hereby incorporated by reference, discloses a novel system and method for photolithography which provides a moving pixel image onto specific sites on a subject. A xe2x80x9csitexe2x80x9d may represent a single pixel, or a group of pixels, depending on the embodiment. In one embodiment, the method projects a pixel-mask pattern onto a subject such as a wafer. The method provides a sub-pattern to a pixel panel pattern generator such as a deformable mirror device or a liquid crystal display. The pixel panel provides a plurality of pixel elements corresponding to the sub-pattern that may be projected onto the subject.
Each of the plurality of pixel elements is then simultaneously focused to discrete, non-contiguous portions of the subject. The subject and pixel elements are then moved (e.g., by vibrating one or both of the subject and pixel elements) and the sub-pattern is changed responsive to the movement and responsive to the pixel-mask pattern. As a result, light can be projected into the sub-pattern to create the plurality of pixel elements on the subject, and the pixel elements can be moved and altered, according to the pixel-mask pattern, to create a contiguous image on the subject.
Certain improvements are desired for maskless photolithograph systems in general, such as the above-described system and method. These improvements increase exposure area, increase exposure intensity, and/or handle errors in the pixel panel.
A technical advance is achieved by a novel system and method for photolithography which provides a digital image from a pixel panel onto one or more specific sites on a subject. In one embodiment, the system includes a panel for generating the pattern and for creating a plurality of pixel elements. The pixel elements are simultaneously directed to a first site of the subject by one or more lenses. The system also includes a manipulator for moving the pixel elements, relative to the subject, to a second site of the subject so that a portion of the second site overlaps a portion of the first site. In some embodiments, the first and second sites are pixel-sites created by a single pixel of the panel.
In some embodiments, the panel is a micro mirror array for selectively reflecting light on and off to create the respective pixel elements. In other embodiments, the panel is a liquid crystal display for selectively allowing light to pass, thereby creating an on/off effect with the respective pixel elements.
In some embodiments, the manipulator further moves the pixel elements, relative to the subject, to a third site of the subject, so that a portion of the third site overlaps a portion of the first site. In some of these embodiments, the portion of the first site overlapped by the second site is the same as the portion of the first site overlapped by the third site.
In some embodiments, the manipulator is a mechanical device for physically moving the panel, relative to the subject. In some embodiments, the manipulator is a rotating prism with a first portion for moving a light path for the pixel elements to a first offset, and a second portion for moving the light path for the pixel elements to a second offset.
In some embodiments, the manipulator is an optical device for optically moving a light path for the pixel elements, relative to the subject. The manipulator may be a rotating optical device for selectively moving a light path for the pixel elements, relative to the subject. Alternatively or in addition, the manipulator may include multiple optical devices for moving a light path for the pixel elements in two dimensions, relative to the subject.
In some embodiments, the panel includes a first and second portion, each for creating corresponding portions of the plurality of pixel elements. In these embodiments, the system also includes an optical element, such as a beam splitter, for combining the pixel elements from the first portion of the panel with the pixel elements from the second portion of the panel so that both portions of pixel elements are directed to the substrate. In some embodiments, the first and second portions of pixel elements are adjacently provided to the substrate. Alternatively or in addition, the first and second portions of pixel elements may overlap each other.
In another embodiment, the system includes first and second panels for creating a first and second plurality of pixel elements, respectively. An optical element combines the first and second elements so that they are simultaneously projected onto a first site of the subject.
As a result, certain improvements are obtained. For one, errors or faulty pixels in the pixel panel are compensated. Also, in some embodiments the exposure area is increased, while in other embodiments the exposure intensity is increased. Furthermore, diagonal projections are better accommodated. Additional benefits can be readily seen from the attached drawings and the foregoing description.